so i have a friend that has a compass that has started having cooling issues. what happened is that the temp , while driving, go up to about 3/4 of the way up. i would turn the heater on and it would drop to 1/2, no immediate, but i would. i was thinking it had an air bubble in the cooling system because his cap was bad (broken seal, could see residue of old coolant on intake man, and plastic cover). replaced the cap, bled the system as much as i could, and still had the same problem. so i was thinking it could be a bad tstat. took them out and tested them. the 203 degree one would not open. so i replaced it, bled the system as much as i could and it still did the same problem. so i said screw it and put a new 170 degree in as well, now both are new tstats. bled the system and topped off the coolant, same issue still. then i was getting irritated and i took them both out for giggles. bled the system, topped off the coolant and it stayed at 1/4 idling in my driveway. i let it idle for about 15+ min and it creeped up to 1/2, then the fans kicked on. let it idle for another 10 and it went to 3/4. at this point i am dumbfounded, so i took it for a spin around the block to put a lot of air through the rad. the temp dropped to about 1/8th like i thought it would. i let it idle in my driveway for about another 10 and it didnt get above 1/4. im still dumbfounded. i dont want to run the car without any tstats in it, so here are my questions:

why would it act this way with good tstats?
would it be a water pump issue?
am i blind or is there any sort of bleeder valve for the cooling system?
is this a problem with compasses and should my friend just trade it in? (lol)

i didnt see any oil in the coolant or coolant in the water or any other signs of a blown head gasket. there are no leaks in the system and the heater blows warm. i dont believe there to be any air bubbles in the system at this point, but it acts as there is when the tstats are in there. any help would be greatly appreciated as i am just scratching my head to figure this out.

Ever had coolant changed and flushed? Sounds to me like like corrosion and blockage and bad circulation through the radiator itself. It works until the engine is pushed hard or sits and idles a long time.
Turning on the heater helps because the raditator isn't doing and efficient job. Water pump seems fine to me, otherwise flow through the heater core would not be good either.

wow.... thanks for the help guys. 104 views and not one single bit of advice. does the jeep community just not help each other or what?

Not exactly the way to get help bud!!!!!!

The reason nobody answered is cus we don't have one for you. Just as you're stumped, so are we. We just kept our mouths shut rather than post for the sake of posting. If it's random posts you want we can drum some of those up if you'd like though.

one thing. going to a colder tstat will cause other issues down the road. New cars/anything run hotter for many reasons. I think the one advice is spot on. I bet no one ever changed the fluid. These new coolants can go FUBAR if left in to long.

as for the community, were are talking a compass. Not like many of these owners are even on this site. think about it.....

as for the community, were are talking a compass. Not like many of these owners are even on this site. think about it.....

Done.

Not a lot of owners on this site because of that attitude...

I'm on a dedicated jeep patriot forum (with a TON more activity) and I have not seen this issue, and that's why I looked and did not respond.

as stated above, there isn't a whole lot to the cooling system. You've changed out the t-stat, bled the system, last thing is new coolant, which should be replaced every 3-5 years. maybe a new radiator? it might be clogged, corroded, or have a lot of bent fins causing it to not be as efficient. If that doesn't do it, maybe have the fluid checked for exhaust? (bad head gasket?)